Pipe bending apparatus



Nov. 23, 1943.

W. L. ENGHAUSER PIPE BENDING APPARATUS Filed March 2'7, 1942 2 Sheets-Sheet 1 Nov. 23, 1943. w ENGHAUSER 2,335,113

PIPE BENDING APPARATUS Filed March 27, 1942 2' Sheets-$heet 2 W. l)fINVENTOR.

A rragvrs yr Patented Nov. 23, 1943 PIPE BENDING APPARATUS Winford L. Enghauser, Cincinnati, Ohio, assignor to The Production Plating Works, Inc., Lebanon, Ohio, a corporation of Ohio Application March 27, 1942, Serial No. 436,480

4 Claims.

This invention relates to the art of bending pipe and is particularly directed to improvements in pipe bending or forming machinery. This type of machinery employs opposing dies which are brought together upon the pipe to bend it as desired.

The chief problems concerned in the bending of pipe are those pertaining to prevention of collapse of the tube walls, that is to say, flattening or deformation of the normal circular cross section of the pipe. Since the pipe is bent cold, it will be appreciated that the prevention of deformation of the cross section is a considerable problem.

Accordingly, it has been an object of the present inventor to provide a pipe bending press or pipe forming machine which incorporates an improved die arrangement effective for pressing the pipe into the desired bent condition without collapsing the tube walls, with particular structural improvements in the die means where it engages the pipe directly at the bend.

It has been an object to provide improvements in the structure for mounting the dies within the press so that they may move relatively in the performance of certain functions of the bending process.

It has been a still further object of the present inventor to provide a pipe bending machine wherein the dies are adjustable to produce bends of varying angularity.

It has been a still further object of the present inventor to provide a die element incorporated in the machine which will engage the pipe at the bend in such manner as to support the side walls of the pipe. that is, those portions of the wall which would tend to spread as the bending pressure is applied.

Other objects and certain advantages of the invention will be more fully apparent from the following description of the drawin s, in which:

Figure 1 is a front view of the improved pipe.

forming mechanism, showing the piece of pipe in position with the upper die descendin Figure 2 is a view taken similarly to Figure 1, but showing the die fully descended and the pipe formed to include the desired bend.

Figure 3 is a sectional view taken crosswise of the dies, showing them in the position illustrated in Figure 2, but with the pipe removed for purposes of illustration.

Figure 4 is a fragmentary side view of Figure 3. further illustrating the dies.

Figure 5 is a view taken similarly to Figure 1, showing a modified and adjustable type of die mounting.

Figure 6 is a side view of Figure 5,

Figure 7 is a sectional .view taken on line l--l, Figure 5, detailing the construction of the central-die element and its relationship to the pipe as the dies descend.

Figure 8 illustrates a further development of the pipe bending operation, wherein the exact part of the pipe being bent is sustained against lateral spreading or deformation.

Generally speaking, the apparatus disclosed herein consists of upper and lower clamping dies, the lower die being supported in a stationary position and adapted to support the length of pipe to be bent. The upper die is movable and is actuated so as to descend upon the pipe, forcing it into the lower die, the cooperation of the dies producing the requisite bend.

Referring specifically to the drawings, the upper and lower dies are generally indicated at I0 and II respectively. The lower die is supported upon a member l2 which is a part of the press structure. trate the press for the supporting means for the lower die and the actuating means for the upper die are conventional. The lower die ll consists of a main body l3 and replaceable die members l4-I4 supported upon adjacently inclined surfaces l5-l5 of the body element I3. The body element is held in position by means of clamping blocks l6l6, the feet of which are attached to the support by means of screws I1. These clamping blocks include vertical grooves for receiving the respective sides of the element l3 and thus, the blocks not only prevent lateral displacement of the die, but displacement rearwardly and forwardly as well.

The clamping die elements M-l 4, as stated, are

ment l3. These dies do not extend into contact,

but rather are spaced apart at their converging ends. Their forming surfaces include longitudinally disposed arcuate grooves 2!, which grooves have an arcuate contour corresponding to that of the pipe thereby formed. These grooves 2| are continued across the upper ends of the dies and the upper ends of the element l3, as indicated at 22. As illustrated in Figure 1, the pipe to be bent. indicated at 23. normally rests in the horizontal extensions of these grooves.

The upper die construction is as follows. A supporting plate 25 is secured to the underside of the ram 26 by means of screws 21, the lower ends of which are shown screw-threaded into the plate 25.

The upper die proper includes a body portion 28 and the die elements themselves, indicated at 29-19. These die elements are secured upon the body at right angles to each other in such man It is not believed necessary to illusner as to engage perfectly in the V or angular relationship of the lower dies. The elements 2929 are mounted in grooves 30 of the body element 28 and are held in these grooves by means of a key 3| and the screws 32 in a manner similar to that employed to secure the lower dies. into position. These die elements include longitudinal arcuate grooves 33, corresponding in shape to the cross section of the pipe. Thus, when the dies engage, as shown in Figure 3, the grooves combine to exactly enclose the pipe.

The die is maintained in assembly or is supported upon the plate by means of headed screws 3d34. The lower ends of these are threaded into the body 28 and are further held posed between the supporting plate 25 and thedie. These springs are of the coil type and are socketed within recesses 38 in the respective elements, that is, the plate 25 and the die body 28. The springs tend to urge the die element away from the plate 25 at all times and have the function of permitting further downwardmovement of the ram after the dies are engaged. This function is described later. The studs 34, plus a central stud 39, maintain the die in assembly position as on the ram.

A forming die til isv provided between the converging lower ends of the dies 2929. This die has a movement independent of the other dies, effective for engaging the pipe to be bent and performing the final bend setting die action. This die element is pinned to the lower end of the stud 39 against the shoulder 4|. The throat of the die is best illustrated in Figures 7 and 8. Although the die surface is in the nature of a groove 52, merging with the respective grooves 3333 of the dies 2529, its groove is of a special contour. It does not correspond to the circular contour of the pipe, but rather, its base circle is of slightly less diameter than that of the external diameter of the pipe.

-As the pipe is first engaged and bent, this central forming die engages and impinges upon the pipe as shown in Figure 7. However, after the dies have come together to bend the runs of pipe into the desired angular relationship, the central shaft die til has an independent further movement. As it is then forced downwardly, it tends to squeeze the side walls of the pipe together as shown in Figure 8, thus. offsetting any tendency of the pipe to flatten in a dire tion at right angles to the aforesaid side walls. 1

It will be seen that the tendency would be to flatten the pipe materially as the bending takes place. In thus engaging the pipe, it is squeezed into a slightly oval shape in a direction reverse to that in which it would ordinarily be deformed.

Although the pipe to be bent is usually malleable and hardly can be referred to as having a spring temper, it will spring a little and the walls thus compressed will return to virtually round. condition when the pipe is released from the dies and the metal takes its set.

This central stud, supporting the central die, slides freely in a vertical central bore of the die body 28. Its upper end includes a shoulder 44 adapted to engage a shoulder 45 in the counterbored portion of the plate 25. The upper end of the reduced diameter portion of the stud carries a pair of nuts 55 also disposed within a counterbored or recessed portion of the bore in the plate 25. When the die is in upper position, the nuts rest upon the shoulder of the plate for supporting the upper die assembly and the shoulder 44 is clear of its shoulder, that is, spaced from it.

As the upper die descends upon the lower die,

the central die contacts the pipe, forcing it to an angular position between the dies. When the dies come into contact, the springs compress and the ram moves downwardly relative to the general upper die. assembly. This results in engagement of the shoulders 44 and 45 of the stud 39 and the plate 25, and further continued movement produces a slight downward movement of the central die independently of the main die assembly with the counter-pressure applying action, described previously, taking place. The, heads of the attaching screws 34-34 have free movement in their recesses in the plate 25. They do not interfere with the final action of the central die.

The pipe bending apparatus described heretofore is designed to provide a right angle bend in the pipe. It is, of course, desirable to arrange the dies so that they will form bends of varying angles and for this reason, the modified structure of Figures 5 and 6 is provided. In the disclosure of this form of the invention a base 58 is provided for supporting the lower die mechanism. A central portion of this base includes lugs 5i providing a space therebetween longitudinally of the base. The lower die elements 52 have their lower ends pivoted between the re. spective ends of these lugs 5! by means of pivot bolts 53 traversing the lugs and the lower ends of the dies and held in position by means of the nuts 54. These die elements include longitu dinal grooves 55 for receiving the pipe in the bending operation.

Adjusting elements 55 are slidably mounted in grooves 57 longitudinally of the base. Gib plates 58 hold these elements 56 in position, overhanging the lateral foot extensions of the elements 56 for this purpose. Each end of the bases carries a bracket 59 and anadjusting screw 6i] is screwed through the bracket against the outer end of the element 56. A look nut holds this adjusting screw in position when apredetermined position has been reached. The upper ends of the adjustment elements are rounded as at BI and contact the upper, outer surfaces of the die elements. These elements 56 will swing the die elements as the elements 55 are moved in and out by means of the adjustment screws.

The die elements are held in contact with the upper ends of the adjustment members by means of coil springs 62 disposed under tension between pins 6353 on the die elements and adjustment elements respectively. It will be quite apparent that the adjustment of the elements 5656 inwardly or outwardly along the base will be effective for changing the angularity of the die relationship.

The upper die assembly consists of a body element 55 and dies 65-65 pivotally mounted on the die body. The die body is mounted relative to the ram 25 and the plate 25 in the same manner as the preceding form of the invention, and the same numerals are used in indicating the springs and the studs. The die body is bifurcated, as shown in Figure 6, and the lower ends of the dies are disposed between the bifurcations, being traversed by pivot bolts 6'l-fil. These bolts pass through vertical slots 58 in the respective sides of the bifurcated body. An adjustment element 69 is disposed horizontally between the arms of the bifurcated body and includes rounded ends engaging the upper surfaces of the angularly disposed die elements.

This adjustment member is held downwardly and adjusted against the dies by means of a pair of vertically disposed screws H screwed downwardly through the upper end of the body element and having their lower ends loosely traversing bores 12 in the adjustment element. Nuts 13 on these screws engage the top of the adjustment member and are adjusted on the stationary screws for moving the member downwardly or permitting it to be moved upwardly. A coil spring 14 is disposed under tension between pins 15 on the upper ends of the respective die elements. This spring tends to pull the die elements into sharper angularity and holds them against the rounded ends of the adjustment member.

The action of the central die member is the same in this form as in the preceding form, that is to say, after the die elements engage and the pipe is bent to the appropriate angle, the bend itself is set so as to prevent flattening in a horizontal plane. This stud, carrying the central die, loosely traverses the bore 16 centrally of the adjustment member 69. Thus, by adjusting the adjustment members 56 and the adjustment members 69, the dies may be adjusted to the desired angularity and may be set so as to correspond perfectly as to their respective angularities, whereby they abut in, perfect alignment when brought together. The length of pipe 22 is shown in fully bent position in Figures 2 and 5.

These dies are not only adjustable for varying angularity, but the upper dies may be adjusted so as to accommodate pipe of difierent diameter. Sets of dies may be supplied providing grooves for the one cross section for each particular case. The dies are easily removable merely by removing the pivot bolts. After the dies have been set to the angularity desired and the upper dies positioned against the lower dies with the ram in lowered position, the pivot bolts are tightened and the nuts 13 are tightened. The vertical slots permit this vertical change of position of the pivots for the upper dies.

Having described my invention, I claim:

1. In a pipe bending machine, two sets of dies relatively movable to and from each other to bend the ends of the pipe to an angle to each other, the dies of the set forming the outer side of the bend of the pipe consisting of two concave die members spaced from each other and mounted at the angle to which it is desired to bend the pipe, said dies contoured to clamp the unbent ends of the pipe and so spaced that the bend of the pine is formed in-between them, the set of dies adapted to form the inside of the bend of the pipe consisting of two clamping dies angularly mounted and spaced apart, said clamping dies complementary to the clamping dies adapted to form the outside of the bend of the pipe, and a central forming die mounted between the dies for clamping the inside of the bend of the pipe, said central forming die adapted to impinge upon the side walls of the pipe to produce a bent pipe which, upon release from the dies, is substantially circular in cross section.

2. In a pipe bending machine, two sets of dies relatively movable to and from each other to bend the ends of the pipe to an angle to each other, the dies of the set forming the outer side of the bend of the pipe consisting of two concave die members spaced from each other and mounted at the angle to which it is desired to bend the pipe, said dies contoured to clamp th unbent ends of the pipe and so spaced that the bend of the pipe is formed in-between them, the set of dies adapted to form the inside of the pipe consisting of two clamping dies angularly mounted and spaced apart, said clamping dies com- 'plementary to the clamping dies adapted to form the outside of the bend of the pipe, and a cen tral forming die mounted between the clamping dies at the inside of the bend of the pipe, said central forming die shaped to bend the pipe by impinging upon the side walls of the pipe during the bending operation to produce a bent pipe which, upon release from the dies, is substantially circular in cross section.

3. In a pipe bending machine, two sets of dies relatively movable to and from each other to bend the ends of the pipe to an angle to each other, the dies of the set forming the outer side of the bend of the pipe consisting of two concave die members spaced from each other and mounted at the angle to which it is desired to bend the pipe, said dies contoured to clamp th unbent ends of the pipe and so spaced that the bend of the pipe is formed in-between them, the set of dies adapted to form the inside of the bend of the pipe consisting of two clamping dies angularly mounted and spaced apart, said clamping dies complementary to the clamping dies adapted to form the outside of the bend of the pipe, and

. a central forming die mounted between the dies for clamping the inside of the bend of the pipe, said central forming die shaped to impinge upon the side walls of the pipe during the bending operation and to compress the side walls of the pipe slightly after the bending operation, means for moving the forming die to bend the pip to the desired angle, and means imparting additional motion to the forming die to compress the pipe laterally to produce a bent pipe which, upon release from the die, is substantially circular in cross section.

4. In a pipe bending machine, two sets of dies relatively movable to and from each other to bend the ends of th pipe to an angle to each other, the dies of the set forming the outer side of the bend of the pipe consisting of two concave die members spaced from each other and mounted at the angle to which it is desired to bend the pipe, said die contoured to clamp the unbent ends of the pipe and so spaced that the bend of the pipe is formed in-between them, the set of dies adapted to form the inside of the bend of the pipe consisting of two clamping dies angularly mounted and spaced apart, said clamping dies complementary to the clamping dies adapted to form the outside of the bend of the pipe, a central forming die mounted between the dies for clamping the inside of the bend of the pipe, said central forming die adapted to impinge upon the side walls of th pipe to produce a bent pipe which, upon release from the dies, is substantially circular in cross section, and means for adjusting both sets of clamping dies to vary their angular relationship and maintain them in parallelism.

WINFORD L. EN GHAUSER.

CERTIFICATE OF CORRECTION. Patent No. 2,555,115. November 25, 1915.

WINFORD L. ENGHAUS-ER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, sec- 0nd column, line 8, claim 2, before "pipe" insert -bend of the-; and that the said Letters Patent should be read with this correction therein that I the same may conform to the record of the case in the Patent Office.

Signed and sealed this 14th day of January, A. D. 19th,.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

